If you can’t buy it, make it

After four employees at BHP Billiton Mitsubishi Alliance’s Blackwater coal mine found a gap in the Australian standard for the brake testing of wheeled earth-moving machinery, they went ahead and developed a new complementary test.

The test helped the mine win this year’s Excellence in Mine Occupational Health and Safety (OH&S) Award sponsored by Sandvik part of Australian Mining’s 3rd Annual Prospect Awards.

Australian Standard 2958.1, which applies to self-propelled rubber-tyred vehicles such as excavators, graders and loaders, only covers the testing of fully-loaded trucks, according to BMA Blackwater’s maintenance manager Peter Townson.

Given a fully loaded Blackwater coal truck weighs in at more than 400 tonnes, immediate testing under these conditions introduces an element of “obvious risk”, Townson says.

“There was no fully defined procedure and training package for conducting and interpreting dynamic brake testing for heavy earth-moving equipment at Blackwater mine,” he said.

So, first up, the team involved established testing criteria for unloaded trucks. The main elements include allowable stopping distances and G-forces associated with deceleration.

Then came the development of testing and training procedures. Blackwater’s ancillary services superintendent David Kirk and tradesmen Greg Mann, Jack Sainsbury and Sam Lichos were instrumental in seeing these completed and, says Townson, “showed the initiative and determination to address this major problem on our site”.

Now, when a truck’s brake system has undergone repairs or major maintenance at Blackwater, the truck is first tested unloaded. The truck is moved to a brake test-pad and a brake test instrument is fitted inside the truck. After the designated speed is reached, the brake is applied until the truck wheels halt. The test instrument prints out the truck’s performance results, which can then be taken away and analysed. Two tests runs are done and provided the truck passes, it goes on to be tested while fully loaded. Otherwise, the truck’s brakes undergo further maintenance or repair work.

According to Townson, alongside safer machinery, the benefits of the new testing regime include improved safety during testing, early detection of brake system defects that would not otherwise be evident, and consistency in test results and their interpretation. He said this system of dynamic brake testing has also been extended to other types of equipment at the mine.

According to details reported recently in a BMA in-house newsletter, the Queensland Mines Inspectorate wanted the testing package used on all mine sites.

In August, judges awarded BMA Blackwater’s brake test with a 2006 Queensland Mining Industry Health and Safety Innovation Award. The awards were run by conference hosts the Queensland Resources Council; the Queensland government’s Department of Natural Resources, Mines and Water; the Construction, Forestry, Mining and Energy Union; and the Australian Workers Union. Another recent innovation that helped Blackwater earn its Australian Mining OH&S excellence award is the dragline high-voltage cable plug adaptor.

When high-voltage cables supplying electricity to a dragline need to be unconnected or reconnected, it typically involves manual handling not only a cable plug weighing about 25 kilograms, but also the trailing cable itself. Because loads are handled in the confines of the dragline’s tub – the weight-bearing base allowing the upper parts of the machine to swivel around a vertical axis – the risk of sprain and strain injuries to the crouching worker is high.

Another issue associated with any cable work inside a tub is the logistical difficulty of rescuing a worker who is inside the tub. “Some innovative thinking from the shop floor identified a way of creating an opening in the dragline tub that did not compromise its structural integrity,” Townson told Australian Mining. A rolling trolley designed in tandem with the tub opening allows a cable plug to be changed over without the need for anyone to enter the dragline’s tub.

According to BHPB’s sustainability report, nothing like this was commercially available at the time. The new set up was also said to increase dragline availability thanks to shortened downtime. In its own 2005 sustainable development report, BMA said it would be fitting out all its draglines with the plug adaptor system when each was due for a major maintenance shutdown. At the time, the company had 34 draglines operating at its seven open-cut coal mines.

* Disclosure: In 2002, a relative of the author died from injuries suffered at the Blackwater mine while he was working on-site for an electrical contractor. Modifications to the type of crane involved are now mandatory at all BMA sites and have been incorporated into an Australian Standard.

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